Aleutian Island Report Card - 2021

Aleutian Islands 2021 Report Card (pdf)

For more information on individual Report Card Indicators, please see Description of Report Card indicators (p. 126). For more information on the methods for plotting the Report Card indicators, please see ”Methods Description for Report Card Indicators” (p. 125).

* indicates Report Card information updated with 2021 data.

To highlight the spatial dynamics and east to west gradients characterizing the Aleutian Islands, we divide the ecosystem into three ecoregions: the Western, Central and Eastern Aleutian Islands.

Region-wide

  • The North Pacific Index (NPI) effectively represents the state of the Aleutian Low. Above (below) average winter (November - March) NPI values imply a weak (strong) Aleutian Low and generally calmer (stormier) conditions. The NPI was above average during the winter of 2020-2021 before returning to near average again in summer 2021. The NPI has been above average for the last 5 winters.
  • The Aleutians Islands region experienced suppressed storminess through fall and winter 2020/2021 across the region, favoring seabird foraging (Bond et al., 2011).

Western Aleutian Islands

  • The reproductive success of least and crested auklets, all planktivorous seabirds at Buldir Island was in above the long term average in 2021, indicating that overall zooplankton availability was sufficient to support seabird reproductive success in 2021 and potentially other plankton eating commercial groundfish species.
  • Forage fish trends, as indicated by their percent in the composition of tufted puffin chick meals, have varied over the long term, with episodic peaks lasting 1–2 years. In general, Ammodytes (sand lance) have been absent starting 2010; age-0 gadids (pollock mostly), which had not been seen in great abundance since 2006, were above the long term average this year although not as abundant as in years past; and hexagrammids (primarily atka mackerel) were near average, improving from last year, thus signaling potentially favorable conditions for fish foragers. Not shown here, rockfish comprised 25% of tufted puffin chick meals. There were no seabird diets collected in 2020.
  • Pelagic forager biomass, apex predator biomass and Steller sea lion (SSL) non-pup counts were not updated this year.
  • The amount of area trawled increased in 2020, continuing its increasing trend since 2014, then last year a 4-year decline following measures aimed at increasing protection for Steller sea lions during 2012–2014. This increase is likely due to a rise in non-pelagic trawl effort. Commercial fishing patterns may reflect recent changes in economics, ownership, and fishing effort allocation. Trawled area has 3 remained within 1 to 3% through the time series. Note this indicator is updated annually with data for the previous year.
  • There are no schools in the western Aleutian Islands ecoregion.
  Mean Trend  
*North Pacific Index (Nov-Mar average)
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*Western AI Least Auklet reproductive success
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*Western AI Crested Auklet reproductive success
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*Western AI Ammodytes in Tufted Puffin diet
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*Western AI Gadids in Tufted Puffin diet
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*Western AI Hexagrammids in Tufted Puffin diet
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Western AI Pelagic Forager Biomass
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Western AI Apex Predator Biomass
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Western AI SSL non pup counts
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Western AI Habitat Impacted by Trawls
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Figure 1: Region-wide and Western Aleutian Islands indicators. *indicates time series updated with 2021 data

Central Aleutian Islands

  • Pelagic forager biomass, apex predator biomass and Steller sea lion (SSL) non-pup counts were not updated this year.
  • The amount of area trawled increased in 2020, continuing its upward trend since 2015 and following a similar trend as in the western Aleutians. The increase, likely due to a rise in nonpelagic trawl effort, is the highest since 2015 when the percent area trawled was at its lowest following the 2012–2014 increasing protection measures for Steller sea lions. Changes in trawled area follows commercial fishing patterns, which may reflect recent changes in economics, ownership, and fishing effort allocation. Despite this year’s increase, trawled area remains within 1 to 3% through the time series. Note this indicator is updated annually with data for the previous year.
  • Both Adak and Atka school enrollment has experienced a decline in the past 5 years. This year’s decrease keeps enrollment at Atka at the 10-student threshold that risks closure of the schools, while enrollment at Adak decreased from 18 last year (the highest since 2016) to 15 in October 2020. Decreasing enrollment trends impact the stability to families living in those communities. This indicator is updated anually with data for the previous year.
*indicates time series updated in 2021 Mean Trend  
Central AI Pelagic Forager Biomass
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Central AI Apex Predator Biomass
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Central AI SSL non pup counts
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Central AI school enrollment
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Central AI habitat impacted by trawls
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Figure 2: Central Aleutian Islands indicators. * indicates time series updated with 2021 data.

Eastern Aleutian Islands

  • As indicated by their percent in the composition of tufted puffin chick meals forage fish were not as abundant as in past years with ammodytes (sand lance) at average levels, and both gadids (pollock) and hexamgrammids (atka mackerel) below average. Not shown, euphausiids made up 34% of the chick meals. This suggests puffins continue to respond to chnages in prey availability and that forage fish may not be as available as in other years for fish-eating commercial groundfish. Gadids were more common through the 1990s while hexagrammids are uncommon in this region. There were no seabird diets collected in 2020.
  • Pelagic forager biomass, apex predator biomass and Steller sea lion (SSL) non-pup counts were not updated this year.
  • The amount of area trawled increased in 2020, continuing its downward trend since 2018. Area trawled had been increasing following the 2012–2014 measures aimed at increasing protection for Steller sea lions. Changes in trawled area follows commercial fishing patterns, which may reflect recent changes in economics, ownership, and fishing effort allocation. Despite this year’s increase, trawled area remains within 1 to 3% through the time series. Note this indicator is updated annually with data for the previous year.
  • School enrollment fell for the second year in a row, from its highest in 2019 at 443 students to 414 in October 2020. This is the lowest since the recent enrollment in 2016–17 of 400 and 408 students. This primarily reflects trends in Unalaska, whereas the small communities have either closed schools (Nikolski, in 2009) or are at risk of closure if they fall under the 10 student threshold (False Pass, 10 students and Akutan with 17). As in the case in the central Aleutians, decreasing enrollment trends impact the stability to families living in those communities. This indicator is updated anually with data for the previous year.
  Mean Trend  
*Eastern AI Ammodytes in Tufted Puffin diet
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*Eastern AI Gadids in Tufted Puffin diet
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*Eastern AI Hexagrammids in Tufted Puffin diet
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Eastern AI Pelagic Forager Biomass
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Eastern AI Apex Predator Biomass
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Eastern AI SSL non pup counts
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Eastern AI School Enrollment
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Eastern AI Habitat Impacted by Trawls
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  2014-2018 Mean   2014-2018 Trend
  1 s.d. above mean   increase by 1 s.d. over time window
  1 s.d. below mean   decrease by 1 s.d. over time window
  within 1 s.d. of mean   change <1 s.d. over time window
  fewer than 2 data points   fewer than 3 data points

Figure 3: Eastern Aleutian Islands indicators. * indicates time series updated with 2021 data.